1. Technical Field of the Invention
The present invention relates to mobile positioning systems, and more particularly, to a system for positioning a mobile station within an existing infrastructure of an AMPS/TDMA system.
2. Description of Related Art
Mobile positioning for location based services has become a very desirable feature for many mobile operators. Mobile positioning enables positioning measurements to be made upon a mobile station wherein the position is based upon the cell/sector ID in which the mobile station presently resides and optionally upon a time alignment value. Positioning by this method provides very coarse values but is sufficient for providing information upon services which may be located near a mobile station""s general position, for example, locations of gas stations, restaurants, grocery stores, etc. This type of coarse positioning may also be sufficiently accurate for services wherein the cell/sector areas in which the mobile station is presently located are sufficiently small.
Currently, mobile positioning based upon the cell/sector ID of a mobile station is only available to GSM customers. This service is not available to AMPS/TDMA customers. A mobile positioning system utilized within a GSM system handles a positioning request similarly to a mobile terminated SMS message. The MSC serving the mobile terminal acts as if an incoming positioning request message is a standard mobile terminated SMS (MT-SMS) message, even though the message has nothing to do with SMS. The positioning request and results of the positioning request are transmitted within the GSM network using MAP (mobile application part) messages.
Unfortunately, the mobile positioning solution utilized within a GSM system is not valid within an AMPS/TDMA system due to the technical differences in the mobile architectures. For example, ETSI-MAP signaling is not available within AMPS/TDMA. The AMPS/TDMA system instead uses ANSI-41 signaling. A proprietary signaling scheme similar to that utilized within GSM might be introduced with AMPS/TDMA, however, this would require the mobile positioning center (MPC), mobile switching center (MSC) and home location register (HLR) to be modified in order to understand the newly created signaling messages. Since the HLRs within many AMPS/TDMA systems are provided by a number of different vendors, this would require major reconfiguration compability problems for a mobile network operator.
Furthermore, in order for an AMPS/TDMA system to handle a positioning request in a similar manner as a mobile terminated SMS message within a GSM system, the mobile station identifier which is a unique identifier associated with the mobile station must be made available. However, within an AMPS/TDMA system, when a positioning request comes from a positioning client or application, only the mobile destination number (MDN) (the number dialed when a user is making a call) is known and a solution implemented in a manner similar to a GSM system is not possible. Therefore, some system and method for enabling mobile positioning within the existing the AMPS/TDMA system infrastructure is desired.
The present invention overcomes the foregoing and other problems with a system and method for positioning a mobile station within an AMPS/TDMA system. A positioning node receives a positioning request for a particular mobile station. In response to this positioning request, the positioning node forwards a positioning request identifier to an HLR of the mobile station within a LOCREQ INVOKE message. The HLR forwards the positioning request indicator from the HLR to an MSC of the mobile station within a ROUTEREQ INVOKE message.
In response to the positioning request indicator received at the MSC, positioning data for the mobile station is obtained. This positioning data is forwarded from the MSC back to the HLR within a ROUTEREQ RESPONSE message, and the positioning data is forwarded on to the positioning node from the HLR within a LOCREQ RESPONSE message. The positioning request may then be responded to by the positioning node.